Electropneumatic hammering device



y 1953 o. SPARANO 2,638,749

ELECTROPNEUMATIC HAMMERING DEVICE Filed Jan. 19, 1951 IN V EN TOR.

Orromvo SPA/9A -o Patented May 19, 1953 ELECTROPNEUMATIC HAMMER ING DEVICE Ottorino Spam-no, Turin, Italy, assignor to Henry J. Clay and Joseph Carlino, bothof New York, N. Y., attorneys for Enrico Squeri Application January 19, 1951, Serial No. 206,764.

7 Claims. (Cl. 60-625} This application relates to apneumatic hammering device and is more particularly concerned with a portable electropneumatic hammering device adapted for use in rock breaking, riveting, ramming, chiseling and like operations.

Hammeringdevices of various types are known, for example pneumatic devices operated by-compressed air supplied from an external source. while compressed air hammering devices are widely used, the necessity of providing a continuous supply of compressed air is in some cases a serious disadvantage.

It is the principal object of the present invention to provide an improved pneumatic hammering device.

It is another object of the invention to provide a device of the character indicated whichdoes not require an externalsupply of compressed air.

It is a further object of the invention to provide an electrically-driven pneumatic hammering device which is easy to operate and efficient 1 operation. r

According to the invention I provide a pneue matic hammering device comprising a freely reciprocatable piston adapted to act upon the tool being driven and a second reciprocatablepiston in air-tight communication with the cylinder containing the first piston and driven from a suitable power source, e. g. an electric motor.

It is afeature of my device that the driven piston may be continuously actuated but that the free tool-engaging piston maybe actuated at will and automatically without the use-of switches,

valves or the like. l

It is another feature of my device that it may be embodied in a readily portable form and may be employed with a plurality ofinterchangeable tools for rock breaking, riveting, ramming, chiscling or like operations which require an intermittent striking force. I

Other objects and features of myinvention will be readily apparent from the following detailed description of one illustrative embodiment of my invention and from the accompanying drawing wherein there is shown, in vertical longitudinal section partly in elevation, a portable electropneumatic hammer embodying features of the invention.

Referring to the drawing, the reference numeral I designates a casing in which is rotatably mounted a crankl, the free end 3 of the crank shaft being journalledin bearing 4 carriedin a bearing housing 5 secured in the wall of. easing, l. The driven crank shaft 6 is rotatably mounted m et n I ecure in ear n housing 8., i

. 2 posed in the wall of easing I opposite housing 5, The shaft 6 extends ,exteriorly of the casing I through a flanged sleeve I I! and is provided at its outer end with a sprocket wheel I2. Mounted over the casin I and removably secured thereto, as by screws I4, is a motor I5 having a shaft 16 provided with a sprocket wheel l8. chain 20 connects sprocket wheel I2 with sprocket wheel I8 to provide a direct driving connection between the motor shaft is and the crank shaft 6., A protective housing 22 secured, as by screws 24; to the face of motor 16 and theyflange 25 of sleeve l0 encloses the sprocket chain 20 and the related portions of the device. A cover plate 21 is removably secured, asby screws 28; to housing 22' to permit ready accessibility of the sprocket chain 2!) and the sprocket wheels l2 and I8. The casing l is provided with a plurality of apertures 30 to permit ready influx and efiiux of air.

The-lower end of casing i is provided with an inwardly directed flange and a cylinder 36 having a finned external surface is secured by means of stud bolts 38 between the flange 35 of casing I and a centrally apertured plate 40 which has a downwardly-projecting integral sleeve portion 42.. The outer surface of cylinder 36 is formed with a plurality .of spaced radial fins 44 which are suitably apertured to permitthe passage of stud bolts 38 andwhich are adapted to permit air cooling of the wall of cylinder 36 to provide rapid dissipation of any heat which may be generated therein. On a line slightly below its center line the cylinder 36 is provided with aligned apertures which provide communica-i tion between the interior of cylinder 36 and the atmosphere, for a reason which will be apparent as the description proceeds. Positioned in cylinder 36 is a reciprocable piston suitablyprovided with piston rings 52 and connected'by means of connecting rod 54 to crank 2. The connecting rod 54 is secured to, piston 59 by a pivot mounting 55 which is secured, as by bolt 56, to the piston 50, and the connecting rod 54 is mounted upon the pin 58of the crank 2 by meansof a bearing 60 in the usual manner. It willbefobserved that the lower face 'of the piston 50 is provided with a recessed central portion .62 whereby a clearance is provided between the lower face of the piston 5!] and the inner surfaceof plate 40 when the piston 50 is in its lowermost position with the peripheral portion of, its lower face 63 in-engagement with the plate 40, as shown in the drawing, The piston '50, as may be clearly seen in the drawing, is formed with channels 65 extending vertically through the,

A sprocket it will be observed that various changes and modifications may be madenwithoutideparting from the scope of the invention as defined in the appended claims, and it is intended therefore that all matter contained in the foregoing. description and in the drawing shall be interpreted as illustrative and not in a limiting sense.

What I claim and desire tosecure by Letters Patentiszy w 1 1. A pneumatic hammering,devicecomprising means defining a first cylinder, a driven piston reciprocable in said first cylinder, means defining a second cylinder coaxial with the first,'adjacent ends of said cylinders being in constant communication with one another, a free piston reciprocable in said second cylinder by alternate pressure and suction produced by the reciprocation of said driven piston, a tool having a shank and means for slidably receiving the shank of said tool in the lower end of said second cylinder below said free piston, said tool shank being movable axially between an inner position in which it projects into said second cylinder and thereby limits the downward movement of said free piston and an outer position in which it permits further downward movement of the free piston, a portion of said second cylinder intermediate its ends being provided with an aperture open to the atmosphere and positioned to be covered by said free piston when downward movement of said free piston is limited by said tool shank in its inner position and uncovered when further down ward movement of said free piston is permitted by the tool shank being in its outer position.

2. A pneumatic hammering device comprising means defining a first cylinder, a driven piston reciprocable in said first cylinder, means defining a second cylinder communicating with the first, a piston freely reciprocable in said second cylinder by alternate pressure and suction produced by the reciprocation of said driven piston, a tool having a shank and means for slidably receiving the shank of said tool in the lower end of said second,

cylinder, said tool being movable between an inner position in which it projects into said second cy1- inder and thereby limits the downward movement of said free piston and an outer position in which it permits further downward movement of said free piston, a portion of said second cylinder intermediate its ends being provided with an aperture open to the atmosphere and positioned to be covered by said free piston when downward movement of said piston is limited by said tool shank in its inner position and uncovered when said free piston is in its lowermost position to open to the atmosphere the space between the two pistons.

3. A pneumatic hammering device comprising means defining a first cylinder, a driven piston reciprocable in said first cylinder, means defining a second cylinder of lesser diameter than said first cylinder, said first cylinder and said second cylinder being coaxial and in communication with each other, a free piston reciprocable in said second cylinder, and means for slidably receiving the shank of a tool in the lower portion of said second cylinder below said free piston, a portion of said upper cylinder normally disposed between the ends of said driven piston being provided with apertures communicating with the atmosphere, and said driven piston being provided with passageways extending from the bottom to the side walls thereof, said passageways being positioned in such manner that their outer ends are in alignment with the apertures in the first cylinder when the driven piston is in its lowermost position.

4. A pneumatic hammering device comprising means defining a first cylinder, a driven piston reciprocable in said first cylinder, means defining a second cylinder of lesser diameter than said first cylinder, said cylinders being coaxial and the upper end of the second cylinder being in communication withthe lower end of the first cyline der, a piston freely reciprocable in the second cylinder by alternate suction and pressure produced bythe reciprocation of said driven piston, a tool having a shank and means for slidably receiving the shank of said tool in the lower end of said second cylinder, said tool being movable between an inner position in which it projects into said second cylinder and thereby limits the downward movement of said free piston and an outer position in which it permits further downward movement of said free piston, a portion of said second cylinder intermediate its ends being provided with an aperture opening to the'atmosphere and positioned to be covered by said free piston when downward movement of said piston is limited by said tool shank in its inner position and uncovered when said tool shank-is in its outer position and saidfree piston is in its lowermost position to open to the atmosphere the space between the two pistons.

5. A pneumatic hammering device comprising means defining a first cylinder, a driven piston reciprocable in said first cylinder, means defining a second cylinder of lesser diameter than said first cylinder, said first cylinder and said second cylinder being coaxial and in communication with each other, a free piston reciprocable in said F second cylinder, and means for slidably receiving the shank of a tool in the lower portion of said second cylinder below said free piston, a portion of said upper cylinder normally disposed between the ends of said driven piston being provided with apertures communicating with the atmosphere, and said driven piston being provided with passageways extending from the bottom to the side walls thereof, said passageways being positioned in such manner that their outer ends are in alignment with the apertures in the first cylinder when the driven piston is in its lowermost position, and said lower cylinder being provided with apertures communicating with the atmosphere and being disposed in such manner that they are above the free piston when said free piston is in its lowermost position in said second cylinder,

6. A pneumatic hammering device comprising means defining a first cylinder, a driven. piston reciprocable in said first cylinder, means defining a second cylinder of lesser diameter than said first cylinder, said first cylinder and said second cylinder being coaxial and in communication with each other, a free piston reciprocable in said second cylinder, a portion of said upper cylinder normally disposed between the ends of said driven piston being provided with apertures communicating with the atmosphere, and said driven piston being provided with passageways extending from the bottom to the side walls thereof, said passageways being positioned in such manner that their outer ends are in alignment with the apertures in the first cylinder when the driven piston is in its lowermost position, a tool having a shank and means for slidably receiving the shank of said tool in the lower end of said second cylinder, said tool being movable between an inner position in which it projects into said second cylinder and thereby limits the downward movement of said free piston and an outer position in which it permits further downward movement of said free piston, a por- 

